Page 66 - Concise Pathology for Exam Preparation ( PDFDrive )

2 Acute and Chronic Inflammation 51

Caseous
necrosis

Langhans
giant cell

FIGURE 2.9. A caseating epithelioid cell granuloma with Langhans giant cells (H&E; 100x).

Types of Granulomas

1. Infectious granulomas
(a) Tuberculosis (prototype of granulomatous disease): Caused by Mycobacterium tu-
berculosis, tuberculosis is associated with the formation of caseating granulomas
(granulomas showing presence of central granular debris with loss of all cellular
detail and higher positivity for acid fast bacilli) or noncaseating granulomas (ab-
sence of caseation and low positivity for acid fast bacilli).
(b) Leprosy: It is caused by Mycobacterium leprae. Noncaseating granulomas are typi-
cally seen with or without acid fast lepra bacilli in the macrophages.
(c) Syphilis: It is caused by Treponema pallidum. Gumma formation is the disease
hallmark. Gumma is histopathologically characterized by a central necrotic area
without loss of cellular outline; plasma cell infiltrate with a wall of histiocytes.
(d) Cat scratch disease: It is caused by a Gram-negative bacillus. It typically shows
rounded or stellate granulomas containing central granular debris and large num-
ber of neutrophils.
(e) Deep fungal infections: Fungal granulomas are caused by organisms like histo-
plasma and blastomyces and are typically suppurative (granulomas with neutro-
philic inflammation).
2. Noninfectious or immune granulomas: Granulomas form in response to persistent
presence of nondegradable or particulate material, which incites an immune response.
These are usually noncaseating epithelioid cell granulomas. Examples includes arcoid-
osis and hypersensitivity pneumonitis.
3. Foreign body granulomas are formed as a response to foreign bodies like talc, suture
and intravenous drugs. The foreign material can be identified in the centre of the
granuloma or within the foreign body giant cells which have a haphazard distribution
of nuclei unlike Langhans giant cell.
Q. Enumerate the components of granulation tissue.

Ans. Granulation tissue (Fig. 2.10) has the following components:
1. Newly formed blood vessels (endothelial proliferation or neoangiogenesis)
2. Chronic inflammatory cells
3. Proliferating fibroblasts
4. Extracellular matrix which in comparison to ordinary extracellular matrix is more cellular
and more vascular

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